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Roger Weller, geology instructor

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Glaciers
by Cameron Roxberry
Physical Geology
Spring 2012
           

Glaciers

     Over 70% of the worlds freshwater is in the form of glaciers. Currently 10% of the world's land mass is covered in glaciers - that's 15,000,000 sq km, but during the last ice age glaciers covered 32% of land. Glaciers have formed and receded for the duration of earth’s history. From the first ice age until now, glaciers have changed and affected the worlds landmasses as well as the oceans. A third of the world population is supported by the fresh water from glaciers.
(facts
From:

Description: http://www.theresilientearth.com/files/images/himilayan_glacier_2.jpg
(facts From:   http://jove.geol.niu.edu/faculty/fischer/429_info/429tr)
 

        Glaciers are seasonal in nature. Glaciers store water through one season, and releases water during another. This cycle is not only important for human use, but also for plant growth and animal migration. Due to the fact that glaciers are affected by long term climate change, glaciers are studied and watched closely largely for climate change indicators. Small changes in size from year to year are monitired and help map out global warming charts, as well as indications change over time.
 

Description: http://www.dismuse.com/wp-content/uploads/2010/10/Glacier2_p.jpg
 

        Glaciers are formed when the accumulation of snow and ice surpasses the ablation. As the weight of the snow and ice increases it finally begins to move. Year after year from the thawing and freezing of ice, the glacier begins to take shape and mold the landscape around it. Glaciers have less dense ice from the direct freezing of water under the glacial mass. The air between snowflakes is trapped and the bubbles crate pockets of air in-between the ice.
 

Description: http://js.top-10-list.org/wp-content/uploads/2009/08/Melting-Glaciers.jpg

 

        Once glaciers are formed they are in a constant state of movement until gone. The beginning of the glacier is called the glacier head, and where the glacier is ended is called the glacier foot. The glaciers move over the land that is sat on because of the presence of liquid water. As the pressure increases toward the base of the glacier, the melting point of water decreases, and the ice melts.  Friction that is caused from the movement of the ice also contributes to the melting of the glacier. Friction also makes the bottom of the glacier move slower than the top.
 

Description: http://www.freewebs.com/abbyoneill/Tidewater-Glacier%20AK.jpg
 

        As the glacier moves along its path, it picks up and carries geological structures such as rocks and sediments. When glaciers move through landscapes it causes what is referred to as glacier valleys. This is where the glaciers have carved a large crevice into the surrounding mountains or terrain. The rocks that are picked up and frozen into the bottom of the glacier act as grit in sandpaper. Glaciers are also studied in past geology. By tracking where the ice sheet formed and to where it dropped all of the sediment, scientists can tell past geological conditions and terrains. Rocks that are found at the end of glaciers are sometimes hundreds of miles from rocks similar in nature.
 

Description: http://i.telegraph.co.uk/multimedia/archive/01680/everest-colour_1680638c.jpg
 

        During normal formation of valleys, water normally forms valleys in the shape of a V. In the formation of glacier valleys, ice creates more of a U shape. Glaciation cause the valleys to be deeper, glaciation also causes the valleys to become smoother due to erosion. Once glacier plucking has occurred and the ice sheet has receded, often small mountain lakes form in the left over crevices called tarns. The terrain the glaciers were once formed will forever be changed due to it. Lakes and geological structures are altered and changed. Glaciers have been and continue to be very important in the formation of earth as well as other planets. Without them, valleys, lakes, mountains and our way of lives would be drastically different.
 

Description: http://www.swisseduc.ch/glaciers/earth_icy_planet/icons-03/14-dry-valleys.jpg
 

Since first documented in 1850, glaciers have been recessing; meaning that fresh water supplies in many countries will dwindle. Long term effects of this can go as far as changing levels of the ocean. Even with small change can drastically buts ecosystems into distress. Some scientists and glaciologists have linked this directly to global warming, although this theory is still not proven. The human population as a whole needs to realize just how important and crucial glaciers are to the survival of not only a country, but a world population. Glaciers also act as a mirror reflecting harmful UV rays back into space. So with the melting of glacier due to temperature rise, a snowball effect will take place and global temperature will continue to rise at a more alarming rate.

 

Description: File:Glacial lakes, Bhutan.jpg
 

Bibliography

"Glaciers." 301 Moved Permanently. Web. 25 Apr. 2012.   http://jove.geol.niu.edu/faculty/fischer/429_info/429trips/NIF/Glaciers.htm
"Service Interruption." All About Glaciers, Introduction. Web. 25 Apr. 2012.  http://nsidc.org/cryosphere/glaciers/index.html
Weller, Roger. "Glaciers." Glaciers. Cochise College. Web. 25 Apr. 2012.  http://skywalker.cochise.edu/wellerr/GLGP-illvocab/GLGP-12.htm